Seldomycin factor 5 is a pseudotrisaccharide antibiotic elaborated by the microorganism Streptomyces hofunensis and for which the formula ##STR1## has been elucidated. Seldomycin factor 5 is also identified as XK-88-5. It is a highly active antibiotic, effective against both gram-positive and gram-negative organisms such as Staphlococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Proteus, Enterobacter and Salmonella species. Seldomycin factor 5 is only one of a number of antibiotics produced by the fermentation of Streptomyces hofunensis. The isolation and characterization of seldomycin factor 5 is described in U.S. Pat. No. 3,939,043, issued Feb. 17, 1976.
The nomenclature of the above and following formulas is simplified by the following numbering system ##STR2## in which the carbons of the cyclitol moiety, also known as the 2-deoxystreptamine moiety, are numbered 1 through 6. The carbons of the hexose moiety are numbered with a single prime, 1' through 6', and the carbons of the pentose moiety are numbered with a double prime, 1" through 5".
Microorganisms are known to frequently acquire resistance to aminoglycoside antibiotics by a mechanism known in the art as "R-Factors". Very generally an R-factor is the extrachromosomal genetic capability of biochemically modifying the antibiotic in such a way as to interfere with its antibacterial action, thereby enabling the organism to grow. Some of the known mechanisms of R-factor mediated resistance involve the attachment of a phosphate ester grouping to the hydroxyl group of kanamycin or neomycin analogous to the hydroxyl group at C3' in seldomycin factor 5. It is known in the art that the replacement of an hydroxyl with a hydrogen will frequently overcome such a mechanism of resistance. It is desirable to obtain compounds which exhibit a broad spectrum of activity against strains of organisms which are resistant to other aminoglycosides.